Degradation kinetics of color, antioxidant activity, total phenolic content, and physicochemical investigation of blanched amaranthus leaves puree by FTIR

Résumé

The aim of the analysis was to find the optimal blanching period for Amaranthus tricolor leaves purees (ATP), that would result in the highest retention of total antioxidant activity (TAA), total polyphenol content (TPC), and chlorophyll (Chl) to boost their functional activity. ATP was blanched for 1, 3, 5, and 7 minutes at 70, 80, and 90⁰C for this analysis. The influence of blanching times on physicochemical, TAA, TPC, and Chl values was then studied. The unblanched and blanched puree was investigated using FTIR analysis (90⁰C for 3 min). The variations in moisture content in ATP were not significant in the physicochemical analysis. There is a substantial decrease in ash content and a rise in pH value with increasing blanching time (p<0.05). As the blanching time for ATP was raised, the percent of the water-soluble index improved significantly (p<0.05). Content of TAA, TPC, and Chl in the ATP was steadily reduced as the blanching time was increased. The degradations of TAA, TPC, and Chl of ATP are well fit by first-order kinetic models, with coefficient determination (R²) ranging from 0.86-0.98. The presence of ketone and alcohol is confirmed by the functional group obtained during the FTIR analysis of the sample. The results can promote household blanching as well as the food industry to prescribe a certain blanching period for vegetables to preserve their TAA, TPC, and Chl values.